Jump to content

Windspeed

Members
  • Posts

    4,613
  • Joined

  • Last visited

Everything posted by Windspeed

  1. A broad surface trough has developed east of Nicaragua near 80W in the western Caribbean. General easterly showers and thunderstorms are moving into Nicaragua along its western boundary, though the trough itself is moving very slowly if hardly a westward drift. This area may get tagged an invest tonight or tomorrow. The trough was modeled with considerable confidence in most of the main globals over the past four to five days, however, only the GFS has remained persistent to develop a tropical cyclone out of this feature. The NHC has not yet mentioned the area in their outlooks, but I would not be surprised if they begin mentioning it by tomorrow if a diurnal MCS goes up tonight out over the Caribbean or somewhere central to the trough axis. Confidence in TC genesis will probably remain low unless this gets better modeling support, or at least something begins resolving on the ECMWF as well. If a TC does develop, score this a win for the GFS though -- much like it did with Dorian back in late August out over the MDR.
  2. Well the micro-vortex is the tiny eye we observed with Hagibis. Really this phenomenon is no different than your average microcane or small hurricane eyewall in general, it just takes a very low shear environment + very high maximum potential intensity w/ high TCHP to get something like a Hagibis or Wilma; and even still, the aformentioned type of micro-vortex may still not occur. Otherwise, outer banding influences in the formative stages usually starves off or dissipates a smaller vortex before MPI can be achieved. Usually the intensification phase of the entire tropical cyclone's broader core cuts off or diverts outer low level convergence rather quickly away from a tiny interior vortex, if it happens to exist, while a larger eye or concentric band takes over. This is usually prior to the system even becoming a hurricane or typhoon. It's just a really chaotic and unpredictable process, at least until the main eyeband or core has consolidated, to know how large or small the dominate vort will be. In short, there really isn't a way to model the chaotic nature of such a phenomenon. It is rather part luck on how small and aligned an MCS-induced mid-level vort is in conjunction to the low level vort underneath. If that can resolve and the MPI is sky high, a small vort can become dominant and remain that way through rapid intensification all the way into the sub-900s hPa. But it's really a crapshoot to know the probability of such occurring. Sometimes the original vort max is just larger and remains that way.
  3. Radar confirms that Super Typhoon Hagibis did not actually make landfall on Anatahan Island. The southern periphery of the island got scraped by the core, but the worst conditions of the inner boundary of the eyewall missed just offshore. Again, good example how satellite imagery can be deceiving as it looked like a direct hit in the posts above. Angle of sensor, parallax and lat/long postion of eye is important.
  4. Rare is a better term. I mentioned some others above: Pam, Patricia, Wilma, Gilbert and Allen all had similar structures. There have been a number of others that developed a super intense >5nm micro-vortex eyewall within a much larger banded concentric envelope. Still, it's not something we see with regards to such extreme sub 890 hpa estimated intensities on a yearly basis. Think perhaps once every 5-10 years globally within the satellite era.
  5. Yes, it was inhabited prior to volcanic unrest. The caldera has been active in recent times with a VEI-4 eruption in 2003. Anatahan is a desolate place that nobody has returned to. I should also say that based on angle of satellite and parallax, it may look like a landfall, but we'll need to confirm it with the radar beam out of the N. Marianas. The base of the tiny 3nm wide vortex may actually be missing south of Anatahan though it looks like a direct hit on the island. Edit: Sorry for edits, Tapatalk is being annoying and lagging posts atm.
  6. Well-formed small vortex in the right place at the right time. Nearly all requirements for RI and MPI met at once. Strong banding around such a small vortex will eventually halt this round but there will likely be reintensification after ERC with a larger eye. Having said that, based on sat estimates, peak intensity has been achieved. At this time there isn't much off structurally in comparison to Patricia or Wilma. The eye is doing a trochoidal wobble that may slingshot it right over the island -- a possible sub 900 hPa hit of you've ever seen one.
  7. If there is a silver lining, it's that due to the low soil moisture content and dry airmass in place, humidity has been low in the upper Tennessee Valley. So it's been a dry heat for us. The nights have been very comfortable. Now, of course, for the Piedmont, coastal plain/fall line and areas east and south I am sure it's been miserable. That's not much of a silver lining because obviously we're in a drought. Fortunately we're well past growing season for most crops. My lawn is basically dead and brown. Have not bothered mowing in three weeks. Not even weeds are having any of this...
  8. McLean's Town, one of the communities in eastern Grand Bahama. It's pretty much what you would expect.
  9. MJO has moved into a suppressive phase. But we'll see where everything lines up in about 10 days. In the meantime it should be quiet.
  10. Such development is very typical of the pattern. The fantasy storm is developing out of a SW Caribbean-Central American surface trough/gyre, not entirely different from Nate in '17 or Michael in '18. Essentially westward propagating tropical waves move into contact and interact with said gyre, amplifying low-level convergence. All you need is a decent upper level high in place and voila. Also steering currents and place of cyclogenesis is critical, of course; and some monster storms have developed out of these features over the years: Mitch, Otto, Wilma, Kate, Michael being the most notable. Hopefully anything that does develop remains weak or doesn't go through one of the aforementioned major hurricane landfall scenarios.
  11. Lorenzo should become intense enough to get the N. Atlantic Basin above the century mark for ACE. @ 88.8 we are just above climatological mean of 76.4 for this date in the season. This season should finish well above average as we may have a few more MDR systems. Of course there is always the western Caribbean to watch out for in Oct. At this time, the N. Atl. and N. Indian are the only basins above seasonal average for calendar date. The N. Hemisphere as a whole is below average @ date with 332.3 (373.1).
  12. That's a mean for projected return. It doesn't suggest we are due in another 10-20 years, only that per climatological average, a sub-900 mb landfall occurs within a spread of 102 years. There could be more or less years, or even 300 years between such events. I would need to read the paper in more detail on how they came up with those means. The 265-yr mean seems much too large to me however these are modeled datasets from projections and not historical observations since we do not have measurements prior to the 1800s. There are only a few estimated examples of such strong tempests prior to that due to captain logs or governing records.
  13. Likewise NCEP forecasts a strong heat ridge over the eastern CONUS the remainder of the month into Oct. Don't just assume modeling will follow suite with every MDR to Caribbean system from here on out. It only takes one getting missed by a weakness and slipping under an ECONUS ridge at the right time to end up as far west as the Gulf. Ridge and trough interactions are dynamic, not held within stasis. Even looking at current global modeling, a case in point. Look at the location of fantasy hurricane moving under the ridge into an amped CONUS pattern. That would spell trouble:
  14. There are already TS force sustained winds being observed. I suspect this may be the shortest classified TD on record as they may upgrade momentarily. lol... Somebody want to do the honors and make a thread?
  15. Something I would like to point out as a reminder about the NHC Outlook's hatched regions with respect to potential cyclone development: These are not intended to be a representation of track nor to be confused as track guidance, they are merely to show a most probable region for a disturbance / area of invest to undergo cyclogenesis. Too many times I see reference to these discussed as forecast track, when in reality, any cyclogenesis that occurs could begin to track towards another direction once a system has been classified. For example, 95L's sharp wave axis or area of low pressure could form a vortex at highest forecast probability anywhere within that hatched zone, but the classified depression or tropical cyclone could immediately begin tracking west from initialization, north or even northeast. I am not accusing anyone of this in current discussion with 95L, but I have certainly seen it done here in the past and elsewhere. Additonally, this is also why the NHC will usually use arrows from an invest's location to a hatched region when they feel it will not develop at its current location. In that case, you can assume some track for the disturbance in an official sense, but only to the region of expected higher probs for cyclogenesis. Before any of this, it's just model slag discussion really.
×
×
  • Create New...